Background

Vitamin B6 is also called pyridoxine. It is involved in the process of making serotonin and norepinephrine, which are chemicals that transmit signals in the brain. Vitamin B6 is also involved in the formation of myelin, a protein layer that forms around nerve cells.

Vitamin B6 deficiency in adults may cause health problems affecting the nerves, skin, mucous membranes, and circulatory system. In children, the central nervous system is also affected. Deficiency can occur in people with kidney failure complications, alcoholism, liver scarring, overactive thyroid, problems with absorbing nutrients, and heart failure, as well as those taking certain medications. Mild deficiency of vitamin B6 is common.

High blood levels of the amino acid homocysteine may be a risk factor for heart disease. Taking vitamin B6 supplements with other B vitamins (folic acid and vitamin B12) has been shown to be effective for lowering homocysteine levels.

Vitamin B6 has been studied for the treatment of many conditions, including anemia (low amounts of healthy red blood cells), vitamin B6 deficiency, certain seizures in newborns, and side effects of the drug cycloserine. Evidence in support of other uses is lacking.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)

The recommended daily intake of vitamin B6 is as follows: 1.3 milligrams in men and women ages 19-50; 1.7 milligrams in men aged 51 and older; and 1.3 milligrams in women aged 51 and older. The maximum daily intake of vitamin B6 in adults and pregnant or breastfeeding women over age 18 is 100 milligrams.

For anemia, 25 milligrams of vitamin B6 has been taken by mouth with multivitamins.

For anxiety, 50 milligrams of vitamin B6 has been taken by mouth daily with magnesium.

For birth outcomes, the following doses of vitamin B6 have been taken by mouth: three lozenges daily, each containing 6.67 milligrams of pyridoxine; 6.67-20 milligrams of pyridoxine daily; 1-25 milligrams of pyridoxine HCl daily; and a single dose of 100 milligrams. A dose of 100 milligrams of pyridoxinum hydrochloricum has been injected into the muscle.

For heart disease (high homocysteine levels), 40 milligrams of vitamin B6 has been taken by mouth daily.

For carpal tunnel syndrome, 200 milligrams of vitamin B6 has been taken by mouth daily for 10-12 weeks.

For cognitive function, 20 milligrams of vitamin B6 has been taken by mouth daily for 12 weeks.

For menstrual cramps, 200 milligrams of vitamin B6 has been taken by mouth daily.

For diabetes, 100 milligrams of vitamin B6 has been taken by mouth daily for 14 days.

For high blood pressure, 5 milligrams of vitamin B6 per kilogram of body weight has been taken by mouth daily for four weeks.

For reducing breast milk, 200 milligrams of pyridoxine has been taken by mouth 2-3 times daily for 6-7 days.

For McArdle's disease, 50 milligrams of vitamin B6 has been taken by mouth daily for 10 weeks, without evidence of benefit.

For nerve pain, 6 milligrams of vitamin B6 has been taken by mouth daily.

For nausea and vomiting of pregnancy, the following doses of vitamin B6 have been taken by mouth: 25 milligrams every eight hours for 72 hours; 10 milligrams of pyridoxine HCl every eight hours for five days; and 100 milligrams daily for seven days. Doses of 30-100 milligrams of pyridoxine have been taken by mouth in 1-3 divided doses daily for three days to three weeks.

For premenstrual syndrome (PMS), up to 600 milligrams of vitamin B6 has been taken by mouth, with 100 milligrams daily suggested as the optimal level.

Children (under 18 years old)

The recommended daily intake of vitamin B6 is as follows: 0.1 milligrams for babies aged 0-6 months; 0.3 milligrams for babies aged 7-12 months; 0.5 milligrams for children aged 1-3 years; 0.6 milligrams for children aged 4-8 years; 1 milligram for children aged 9-13 years; 1 milligram for males aged 14-18 years; and 1.2 milligrams for females aged 14-18 years. The maximum daily intake of vitamin B6 is 30 milligrams for children aged 1-3 years, 40 milligrams for children aged 4-8 years, 60 milligrams for children aged 9-13 years, and 80 milligrams for adult males and females and pregnant or breastfeeding females aged 14-18 years.

For atopic eczema (skin disorder causing itchy, scaly rashes) in children over 12 months of age, 50 milligrams of pyridoxine hydrochloride has been taken by mouth for four weeks.

For anemia, 2-25 milligrams of vitamin B6 has been taken by mouth alone or with iron or a multivitamin for up to eight weeks.

For seizures caused by fever, 20 milligrams of pyridoxine has been taken by mouth twice daily for 12 months.

Evidence

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Anemia

Vitamin B6 has been studied for a genetic disorder called sideroblastic anemia, in which the body does not make enough healthy red blood cells. Vitamin B6 supplements have been found to be effective for treating this condition under the care of a medical professional.

A

Nutrition (vitamin B6 deficiency)

Vitamin B6 supplements are effective for preventing and treating vitamin B6 deficiency and nerve inflammation caused by low intake, certain diseases, or some drugs. Dietary supplements should be taken under the guidance of a medical provider.

A

Preventing adverse effects in people taking cycloserine

Cycloserine is a prescription drug that treats tuberculosis or urinary tract infections. It may cause side effects such as anemia (low amounts of healthy red blood cells in the body), nerve inflammation, or seizures. Vitamin B6 has been found to help prevent these side effects.

A

Pyridoxine-dependent seizures in newborns

High doses of vitamin B6 (pyridoxine) in pregnant mothers or genetic disorders may cause seizures in newborns. These seizures may be controlled quickly by a medical professional injecting pyridoxine into the vein.

B

Premenstrual syndrome (PMS)

There is some evidence that taking pyridoxine by mouth may improve PMS symptoms, such as breast pain, depression, or anxiety in some women. Further research is needed before a conclusion can be made.

C

ADHD

Some research suggests that vitamin B6 supplementation used alone or with other vitamins and minerals may help treat ADHD. However, there is conflicting evidence. Further research is needed before a conclusion can be made.

C

Akathisia (disorder causing restlessness and inability to sit still)

Some anti-psychotic drugs may cause movement disorders, such as akathisia. Early study suggests that high doses of vitamin B6 may be helpful when added to standard treatment for this disorder. Further research is needed to confirm these results.

C

Alzheimer's disease prevention

High blood levels of the amino acid homocysteine may indicate Alzheimer's disease risk. Pyridoxine supplements taken alone or with other B vitamins (folic acid) have been found to be effective for lowering homocysteine levels. However, it is unclear whether lowering homocysteine levels also lowers Alzheimer's disease risk. Further research is needed before a conclusion can be made.

C

Angioplasty (surgery for blocked arteries)

There are conflicting findings to support the use of folic acid, vitamin B6, and vitamin B12 together after angioplasty. Further research is needed before firm conclusions can be made.

C

Anxiety

Evidence is lacking to support the use of vitamin B6 for relieving anxiety. More research is needed in this area.

C

Asthma

Early research suggests that children with severe asthma may have low vitamin B6 levels. Theophylline, an anti-asthma drug, seems to lower vitamin B6 levels. Studies of vitamin B6 supplementation in people taking theophylline for asthma have found conflicting results. Further research is needed before a strong conclusion can be made.

C

Atopic eczema (skin disorder causing itchy, scaly rashes)

Supplementation with vitamin B6 has been studied for the treatment of atopic eczema. Early study has looked at the use of vitamin B6 for eczema symptoms in children, but found a lack of effect. High-quality research is needed to make firm conclusions.

C

Birth outcomes

Studies of birth outcomes in which pregnant mothers were given vitamin B6 supplements have found mixed results. Other research suggests that vitamin B6 supplements during pregnancy may help improve dental health and birth weight of babies. More high-quality study is needed in this area.

C

Breast feeding (reducing breast milk)

Early studies have found conflicting results on the use of vitamin B6 for reducing breast milk. Further research is needed before a firm conclusion can be made.

C

Breast tenderness

Evidence is lacking to support the use of vitamin B6 for breast pain or tenderness. More study is needed in this field.

C

Cancer prevention

Some evidence suggests that vitamin B6 lowers the risk of colon cancer. However, a combination of folic acid, vitamin B6, and vitamin B12 did not appear to decrease the risk of breast cancer. There is some evidence that male smokers with higher blood levels of vitamin B6 may have a lower risk of lung cancer. High-quality research is needed to confirm these results. Supplementation is not standard therapy at this time.

C

Carpal tunnel syndrome

Evidence to support the use of vitamin B6 for carpal tunnel syndrome is currently lacking. Early study suggests that people who have the condition may have lower vitamin B6 levels. More research is needed before a firm conclusion can be made.

C

Central nervous system disorders

Early evidence suggests that vitamin B6 supplementation may benefit children with overactive restlessness and low levels of serotonin, a chemical in the brain. Further research is needed to confirm these results.

C

Cognitive function

Early research suggests that poor cognitive function may be associated with low levels of folate in the blood. However, this effect was lacking with vitamin B6. More study on the effects of vitamin B6 alone is needed.

C

Depression

Early study has looked at the use of vitamin B6 for symptoms of depression. Higher blood levels of the amino acid homocysteine may increase the risk for later depression. More studies are needed to confirm potential benefits.

C

Diabetes

Early research suggests that daily vitamin B6 supplementation may improve blood sugar levels in diabetes associated with pregnancy. High-quality research is needed to confirm these results.

C

Fertility in women

Early research suggests that vitamin B6 supplementation may affect female fertility. Vitamin B6 used with other supplements may improve pregnancy outcome. However, strong evidence to support this effect is currently lacking. Further high-quality research on the effects of vitamin B6 alone is needed.

C

Heart disease (high homocysteine levels)

High blood levels of the amino acid homocysteine may be a risk factor for heart disease, blood clotting disorders, clogged arteries, heart attack, and stroke. Vitamin B6 has been studied in combination with other B vitamins (mainly folic acid) for lowering homocysteine levels. Some studies suggest that folic acid may be more effective than vitamin B6, while others report that vitamin B6 alone may lack effect. More research is needed before firm conclusions can be made on the use of vitamin B6 for heart disease.

C

High blood pressure

Early research suggests that vitamin B6 may lower blood pressure. More research is needed to confirm these results.

C

Immune function

Vitamin B6 is thought to be important for immune system function. Early study found positive effects of vitamin B6 on immune response. More research on vitamin B6 supplementation for this use is needed.

C

Kidney stones (general)

Vitamin B6 taken alone or with magnesium may reduce the risk of certain types of kidney stones. Higher vitamin B6 intake has been linked to a lower risk of developing certain kidney stones in women, but this effect was found to be lacking in men without a history of kidney stones. Further studies are needed before a firm conclusion can be drawn.

C

Kidney stones (calcium oxalate stones)

Vitamin B6 taken with other treatments may help maintain kidney function in people with hyperoxaluria, in which excessive amounts of a compound called oxalate are found in the urine. People who have hyperoxaluria often have a high risk for calcium oxalate stones. High-quality research is needed in this area.

C

McArdle's disease

McArdle's disease is a rare, inherited muscle disease that causes fatigue, painful muscle cramps, and muscle failure. Muscle damage in people with this disease may cause dark urine and vitamin B6 deficiency. Early research found a lack of benefit of vitamin B6 for McArdle's disease. Further research is needed.

C

Menstrual cramps

Early research suggests that vitamin B6 may be effective for relieving menstrual cramps. However, evidence is lacking and further research is needed to confirm these results.

C

Osteoporosis prevention

Evidence is conflicting in support of vitamin B6 for bone protection. More studies are needed before a firm conclusion can be made.

C

Pain from nerve disorders

Supplementing with vitamin B6 has been suggested as a treatment for nerve pain. Further research is needed to form conclusions.

C

Pregnancy-induced nausea and vomiting

Studies have looked at the use of vitamin B6 alone or with other anti-nausea treatments in pregnant women, with conflicting results. Further research is needed before a firm conclusion can be made.

It is thought that women who take birth control pills may need to take vitamin B6 supplements, although this lacks scientific proof. Women on low-dose birth control taken by mouth may have lower levels of the vitamin. B6 supplementation should be used with caution, since long-term effects are unknown. High-quality research is needed in this area.

C

Seizures (caused by fever)

Early research suggests that vitamin B6 may lack effect on seizures caused by fever. More research is needed to confirm these results.

C

Tardive dyskinesia (disorder causing uncontrolled movements)

Vitamin B6 has been studied for people who have tardive dyskinesia. Early research suggests that vitamin B6 may be of benefit for symptoms of this condition. Further research is needed before a firm conclusion can be made.

C

Vein clots

Early research suggests that low levels of vitamin B6 may be a risk factor for blood clots in the veins. Further study is needed to form conclusions.

D

Autism

Studies on at the use of vitamin B6 alone or with magnesium have found unclear results for the treatment of autism. Further research is needed. Autism should be treated by a qualified medical provider.

D

Stroke prevention

Vitamin B6 alone or with vitamin B12 and folic acid has been found to lack effectiveness in preventing recurrent strokes. Further research is needed to determine the effect of vitamin B6 alone.

Uses based on tradition or theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Interactions

Interactions with Drugs

Vitamin B6 may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).

Vitamin B6 may affect blood sugar levels. Caution is advised when using medications that may affect blood sugar. People taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.

Vitamin B6 may interfere with the way the body processes certain drugs using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs may be altered in the blood, and may cause altered effects or potentially serious adverse reactions. People using any medications should check the package insert, and speak with a qualified healthcare professional, including a pharmacist, about possible interactions.

Interactions with Herbs and Dietary Supplements

Vitamin B6 may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.

Vitamin B6 may affect blood sugar levels. Caution is advised when using herbs or supplements that may affect blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.

Vitamin B6 may cause low blood pressure. Caution is advised in people taking herbs or supplements that lower blood pressure.

Vitamin B6 may interfere with the way the body processes certain herbs or supplements using the liver's "cytochrome P450" enzyme system. As a result, the levels of other herbs or supplements may be altered in the blood. It may also alter the effects that other herbs or supplements possibly have on the P450 system.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

Avoid in people with known allergy or sensitivity to any ingredient in vitamin B6 products.

Side Effects and Warnings

Vitamin B6 is likely safe when taken by mouth in recommended daily intake amounts. The recommended daily intake of vitamin B6 is as follows for adults: 1.3 milligrams in men and women ages 19-50; 1.7 milligrams in men aged 51 and older; and 1.3 milligrams in women aged 51 older. The recommended daily intake of vitamin B6 is as follows for children: 0.1 milligrams for babies aged 0-6 months; 0.3 milligrams for babies aged 7-12 months; 0.5 milligrams for children aged 1-3 years; 0.6 milligrams for children aged 4-8 years; 1 milligram for children aged 9-13 years; 1 milligram for males aged 14-18 years; and 1.2 milligrams for females aged 14-18 years.

Side effects to some ingredients of high-dose pyridoxine hydrochloride (which is injected into the vein) are possible.

Vitamin B6 may cause low blood pressure. Caution is advised in people with blood pressure disorders or in those taking drugs or herbs and supplements that lower blood pressure.

Vitamin B6 may affect blood sugar levels. Caution is advised in people with diabetes or low blood sugar, and in those taking drugs, herbs, or supplements that affect blood sugar. Blood sugar levels may need to be monitored by a qualified healthcare professional, including a pharmacist, and medication adjustments may be necessary.

Vitamin B6 may increase the risk of bleeding. Caution is advised in people with bleeding disorders or taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.

Use cautiously in people who have heart conditions or stomach and intestine conditions.

Use cautiously in people taking agents for Parkinson's disease, as they may interact with vitamin B6.

Avoid in people with known allergy or sensitivity to any ingredient in vitamin B6 products.

Avoid in doses higher than 200 milligrams daily, due to the risk of nerve pain and seizures.

Avoid high doses during pregnancy or breastfeeding. A special product has been approved by the U.S. Food and Drug Administration (FDA) for use during pregnancy, but it should not be used long-term or in high doses without the guidance of a medical provider, due to the risk of seizures in infants.

Pregnancy and Breastfeeding

Vitamin B6 is likely safe for pregnant and breastfeeding women when taken by mouth in doses not exceeding the recommended daily intake.

Avoid high doses during pregnancy or breastfeeding. A special product has been approved by the U.S. Food and Drug Administration (FDA) for use during pregnancy, but it should not be used long-term or in high doses without the guidance of a medical provider, due to the risk of seizures in infants.

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